[Beaconhunter]

Thanks for all the great tips. I was out driving today, and when experiencing the interference problem, just reached under the dash and disconnnected the coax from the GRE-600 as suggested by DickH. I was surprised to find that this solved the problem! The signal was a little scratchy but perfectly readable. However, when I drove into some areas, I had weak or no signal without the antenna.

I next tried reconnecting the coax, but removed the 800 Mhz antenna from its NMO mount, leaving just the mount itself to act as the antenna. This gave me a signal that sounded roughly the same as when the coax was disconnected from the radio (I was expecting it to be a little stronger). Still not acceptable in weak signal areas.

I then installed a straight 1/4 wave 800 Mhz whip on the NMO mount instead of the 3 db gain antenna I was previously using. This gave me a good signal, but the interference problem was back - but not as bad as when I was using the previous gain antenna. I turned the GRE attenuator on, and this seemed to give me an acceptable compromise between signal strength and interference, but it still is not perfect.

I have an old NMO mount 1/4 wave VHF whip. I am going to try cutting this down to about a half-inch or so to see how it works. I also want to try connecting a BNC connector to the back of the radio that just has a short length of wire dangling from it to see how this works.

If all else fails, I may have to go the antenna switch suggested by DickH and simply disconnect the antenna when in an interference area. I hate the thought of having to manually switch back and forth however...I have enough "driving distractions" as it is..:-)